[GHC] #11417: Missing context in Generics example

12 Jan 2016

      #11417: Missing context in Generics example
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           Reporter:  dfeuer         |             Owner:
               Type:  bug            |            Status:  new
           Priority:  high           |         Milestone:  8.0.1
          Component:  Core           |           Version:  7.10.3
  Libraries                          |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Documentation
  Unknown/Multiple                   |  bug
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 The Haddocks for `GHC.Generics` give an example of a default
 implementation using Generics:

 {{{#!hs
 class Encode a where
   encode :: a -> [Bool]
   default encode :: (Generic a) => a -> [Bool]
   encode x = encode' (from x)
 }}}

 The default signature is missing some context. It should read

 {{{#!hs
   default encode :: (Generic a, Encode' (Rep a)) => a -> [Bool]
 }}}

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11417
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